Question

What range of electromagnetic spectrum is considered as light?

• A. 1 mm to 700 nm
• B. 400 nm to 1 nm
• C. 400 nm to 700 nm
• D. 1 nm to 10\(^{-3}\) nm

Hint:

A useful mnemonic is VIBGYOR. Violet starts at \(\approx\) 400 nm and Red ends at \(\approx\) 700 nm. In \(\text{\AA}\text{ngstr\(\ddot{o}\)ms}\), this is 4000 \(\text{\AA}\) to 7000 \(\text{\AA}\).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the approximate wavelength range of the visible part of the electromagnetic spectrum, which is commonly referred to as "light".
Step 3: Detailed Explanation:
The electromagnetic spectrum consists of waves ranging from very long radio waves to very short gamma rays. The "visible light" portion is a tiny fraction that the human eye can perceive.
- Standard scientific texts define this range as approximately 400 nm (violet) to 700 nm (red).
- In terms of frequency, this corresponds to roughly 430–750 THz.
- Option (1) includes infrared, option (2) includes ultraviolet/X-rays, and option (4) is the range for Gamma rays.
Step 4: Final Answer:
The considered range of light is 400 nm to 700 nm.